(a) Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP having a barrier rib structure between two substrates that defines discharge cells into independent units.
(b) Description of the Related Art
A PDP is typically a display device in which ultraviolet rays generated by the discharge of gas excite phosphors to realize predetermined images. As a result of the high resolution and large screen sizes possible with PDPs, they are quickly emerging as one of the most popular flat panel display configurations.
Depending on a drive voltage applied to a discharge region, that is, depending on the discharge type, the PDP is classified into the different types of the AC-PDP and the DC-PDP. Further, the PDP is classified as an opposing discharge type PDP or a surface discharge type PDP depending on its electrode structure. The PDP having an AC surface discharge structure (i.e., AC-PDP) is becoming the standard configuration.
The general structure of the AC-PDP will now be described. In the conventional AC-PDP, address electrodes are formed along one direction on a surface of a rear substrate. A dielectric layer is formed on the rear substrate covering the address electrodes, and barrier ribs are formed on the dielectric layer. The barrier ribs are formed in a stripe pattern between the address electrodes. Formed between (and often along inner walls of) the barrier ribs are red (R), green (G), and blue (B) phosphor layers. That is, one of the R, G, and B phosphor layers is formed between each pair of barrier ribs.
Formed on a surface of a front substrate opposing the rear substrate are discharge sustain electrodes. Each of the discharge sustain electrodes includes a transparent electrode and a bus electrode. The discharge sustain electrodes are formed along a direction such that they intersect (i.e., are generally perpendicular to the direction of) the address electrodes. A dielectric layer is formed on the rear substrate covering the discharge sustain electrodes, and an MgO protection layer is formed on the dielectric layer.
Areas between where the address electrodes of the rear substrate and the discharge sustain electrodes of the front substrate intersect correspond to where discharge cells are formed.
An address voltage Va is applied between the address electrodes and the discharge sustain electrodes to perform address discharge, then a sustain voltage Vs is applied between a pair of the discharge sustain electrodes to perform sustain discharge. Vacuum ultraviolet rays generated at this time excite corresponding phosphor layers such that visible light is emitted through the transparent front substrate to realize the display of images.
However, in the PDP structured with the discharge sustain electrodes as described above and the barrier ribs provided in a stripe pattern, crosstalk may occur between adjacent discharge cells (i.e., discharge cells adjacent to one another with the barrier ribs provided therebetween). Further, since there is no structure provided between adjacent barrier ribs for dividing the discharge cells along this direction, it is possible for mis-discharge to occur between adjacent discharge cells within adjacent barrier ribs. To prevent these problems, it is necessary to provide a minimum distance between the discharge sustain electrodes corresponding to adjacent pixels. A drawback of doing so, however, is that this limits efforts at improving discharge efficiency.
In an effort to remedy these problems, PDPs having improved electrode and barrier rib structures have been disclosed.
In the PDP having an improved electrode structure, although barrier ribs are formed in the typical stripe pattern, discharge sustain electrodes are changed in configuration. That is, the discharge sustain electrodes include transparent electrodes and bus electrodes, with a pair of transparent electrodes being formed for each discharge cell in such a manner to extend from the bus electrodes and oppose one another. U.S. Pat. No. 5,661,500 discloses a PDP with such a configuration. However, mis-discharge along the direction that the barrier ribs are formed remains a problem with this PDP.
Another configuration adds an improved barrier rib structure to the above structure. In such a PDP, a matrix structure for barrier ribs is used in which the barrier ribs include vertical barrier ribs and horizontal barrier ribs that intersect one another. Japanese Laid-Open Patent No. Heisei 10-149771 discloses a PDP with such a configuration.
However, with the use of the matrix barrier rib structure described above, since all areas except for where the barrier ribs are formed are designed as discharge regions, only areas that generate heat and no areas that absorb or disperse heat are formed. As a result, after a certain amount of time has elapsed, temperature differences occur between cells in which discharge occurs and in which discharge does not occur. These temperature differences not only affect discharge characteristics, but also result in differences in brightness, the generation of bright image stickings, and other such picture quality problems. “Bright image stickings” refers to a difference in brightness occurring between a localized area and its peripheries even after a pattern of brightness that is greater than its peripheries is displayed for a predetermined time interval then returned to the brightness of the overall screen.
Further, in the PDP having the barrier ribs of such a matrix structure, either the phosphor layers are unevenly formed in corner areas that define the discharge cells, or the distance from the phosphor layers to the discharge sustain electrodes is significant enough that the efficiency of converting ultraviolet rays into visible light is reduced.